Muffler



l Juny 18, 1944. w B, -McLEoD 2,353,914

- MUFFLER Filed Aug. 3, 1942 INVENroR. WML/4M 5. McLean BYZ fk l Arroz/vers.

Patented July 18, 1944 UNITED STATES PATENT yoFEicE wuuam B. Mcmsmeles, cani.

Application Allglllt 3, 1942, Serial No. 453,326

Claims.

This invention relates to improvements in muiiiers and constructions designed to silence the exhaust of internal combustion engines,r psrticularly airplane engines or enginesused on aircraft. 4

' A primary object of the invention is to provide an` improved muiller construction which is so designed as to enable the handling of the exhaust gases to effectively silence the noise and let -to the outlet and which has a series of annular cavities formed therein that are closed except around the mentioned passage forming chame bers in which'that portion of the exhaust gases that flows directly through the,r passage may radially expand and thereafter flow toward the outlet. By thus forming a series of such cavities or chambers expansion of the gases is permitted but the transmission of the noise to the outlet is greatly reduced and substantially eliminated.

` Another object of the invention is to provide a muffler having the above-mentioned characteristics wherein the wall forming the outer sides of the cavities is in spaced relation vto the interior of the shell whereby a substantial portion of the exhaust gases may now around these cavities between the outer wall thereof and the interior of the shell and be subsequently directed toward the outlet. In this manner, an opposed turbulence is created in the gases which tends to neutralize itself adjacent the center of the mufer before passing into the outlet. By this construction although the exhaust gases enter the muier in a succession of bursts or puns the noise is effectively eliminated and the gases are quieted so that when they issue from the outlet they issue in the form of a relatively steady stream as distinguished from the incoming bursts or puffs v With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawing for an illustrative embodiment of the invention, wherein:

Figure l is a longitudinal vertical section through the muffler embodying the present invention;` n

Fig. 2' is a vertical section taken substantially upon the line 2-2 upon Fig. 1;

Fig. 3 is a vertical section taken substantially upon the line 3 8 upon Fig. 1;

Fig. 4 is a perspective view of one of the forwardly directed conical baiiies; and

Fig. 5 is a perspective view of one of the rearwardly directed conical bailles.

Referring to the accompanying drawing whereinv similar reference characters designate similar parts throughout, i0 indicates the inlet from the exhaust manifold of an internal combustion engine. Il indicates the outlet from the muiiler. The muflier comprises a shell in the form of an outer sheet metal cylinder kI2 equipped at its ends with\end caps Il and i4 which may be welded or `otherwise secured thereto. On the interior of the shell there is disposed a layer of insulatlngmaterial l5 such as shredded asbestos. This insulation is maintained against the interior of the cylinder I2 such as by a woven wire screen I6. Bars i1 extend longitudinally through the shell from end to end thereof and rest against the interior of the screen I8. These bars are preferably three in number although their num- 2i may be formed integral with the skirt or mayA be attached thereto and these arms are in tum y welded or otherwise secured to the longitudinally extending bars I1. The bames are arranged one behind the other so that the aperatures i9 are in alignmentl with each otherand with the inlet i0.

The edge .if the skirt of each baille is welded or otherwise secured to the juncture of the conical portion of the succeeding baille with its skirt such as is indicated by the welds 22. The skirt portions 20 thus cooperate to define a cylindrical wall around the forwardly directed conical baffles, which cylindrical wall is in spaced relation to the interior of the shell the inner surface of which is formed by the skirt I6. Thus, a series of outwardly and rearwardly divergent annular cavities 23 are formed around the central passage formed by the aligned apertures I9.

At the back of the mufller there is a series of rearwardly directed conical bailles 24. These baiiies are in the form of frusta-conical portions having apertures 25 at their apices that are in alignment with each other with the outlet Il and with the apertures Il. Radial arms 20 are formed integral with these bailles or are otherwise secured thereto and are welded or are otherwise secured to the longitudinally extending bars l1. The rear edge of the rearwardly directed baule 24 is preferably welded to the outlet pipe Il.

The operation of the improved muflier is as follows. The exhaust gases entering the muifier from the exhaust manifold of the internal combustion engine enters through the entrance or through the inlet l in a series of puffs or bursts. A fraction of these gases pass straight through the straight unobstructed passage afforded by the aligned apertures I8 these gases tending to quick- Ly radially expand. Opportunity for expansion is afforded by the annular cavities or chambers 2l which are closed except for the space surrounding the passage provided by the apertures I9. Thus, each puff or burst of incoming exhaust 1 gases has a portion that passes through the apertures i9 and in so doing it merely expands radially into the chambers 23 compressing the residual gas or air that may be present therein. Between consecutive puffs or bursts this compressed gas in each chamber can expand back into the straight, central, longitudinal passage as indicated by the reversely bent arrows in these chambers. The remainder of the incoming gas that enters the muffler from the inlet III is spread by the foremost conical bafne and as indicated by the arrows, this remainder flows rearwardly between the skirt and the screen I8, flowing between the braces or arms 2|. That portion of the gas that has passed through the straight central passage through the muiiler finally encounters the series of rearwardly directed baffles which converge toward the central passage. These gases when encountering these converging surfaces have turbulences developed therein as indicated by the arrows on Fig. l. Those gases which passed on the outside, that is between the skirt 20 and the screen i6, also encounter these converging baffles and as these gases are directed inwardly they have a similar turbulence generated therein. The turbulence on diametrically opposite sides of the rearwardly directed bames is in the opposite direction so that when these opposed turbulences meet in the rear portion of the straight central passage formed by the aligned apertures 2i, the opposed turbulences tending to neutralize each other with the result that the exhaust gases when they enter the outlet Il issue therefrom in a relatively steady stream as distinguished from the incoming puffs or bursts.

By this construction the noise attendant the exhaust gases issuing from the exhaust manifold is substantially eliminated. However, as there is no obstruction within the mufher, back pressure on the interior of the inlet i0 and the exhaust manifold is reduced to such an extent as by merely removing one of the end caps Il or Il. When the end cap is removed the bafiles which are all mounted on the longitudinally extending bar I1 can be withdrawn by sliding these bars longitudinally from within the skirt Il. Thus all bailies can be removed together as a single unit and a substitute unit may be instantly inserted and the end cap replaced.

From the above-described construction it will l0 be appreciated that the improved muilier is of relato be negligible. Consequently, there is no back pressure created by the mufiler in the exhaust manifold that would reduce the eil'lciency of the engine.

While the muffler in its preferred form is cylindrical it will be understood that it may be given any other desired or preferred cross-sectional shape. Thus rectangular, hexagonal, or triangular or oval shapes might be employed if desired.

In the event that the bailles on the interior of the muilier become burned or corroded with use,

it is possible to effect an easy replacement thereof tively simple design, inexpensive to manufacture, and is highly efcient in its operation, reducing the noise but at the same time conducting the gases in such a manner as to prevent the creation of back pressure in the exhaust manifold. Although the invention has been illustrated as incorporated in a muiller that is connected to the exhaust manifold it will be appreciated that it would be possible, in certain instances to embody the invention directly on the interior of the exhaust manifold itself.

Various changes may be made in the details of construction without departing from the spirit or scope of the invention as denned by the appended claims.

I claim:

i. A muflier comprising means providing an outer shell having an inlet adjacent one end and an outlet adjacent the other, there being a continuous straight unobstructed passage through the shell from the inlet to the outlet, means providing a series of outwardly extending cavities within the shell adjacent the inlet, said cavities being closed except around said passage, said cavity providing means being in spaced relation to the inner wall of the shell and from the inlet whereby a portion of the gases entering through the inlet may pass directly into the passage and the remainder of the gases flow around the cavity providing means toward the outlet.

2. A muilier comprising means providing an outer shell having an inlet adjacent one end and an outlet adjacent the other, there being a continuous straight unobstructed passage through the shell from the inlet to the outlet, means providing a series of outwardly extending cavities within the shell adjacent the inlet, said cavities Abeing closed except around said passage, said cavity providing means being in spaced relation to the inner wall of the shell and from the inlet whereby a portion of the gases entering through the inlet may pass directly into the passage and the remainder of the gases' flow around the cavity providing means toward the outlet, and converging means in the shell adjacent the outlet for converging the gases toward said passage before passing into the outlet.

3. A muiiler comprising means providing an outer shell having an inlet adjacent one end and an outlet adjacent the other, there being a continuous straight unobstructed passage through the shell from the inlet to the outlet, means providing a series of outwardly extending cavities within the shell adjacent the inlet, said cavities being closed except around said passage, said cavity providing means being in spaced relationto the inner wall of the shell and from the inlet whereby a portion of the gases entering through the inlet may pass directly into the passage and the remainder of the gases now around the cavity providing means toward the outlet, said shell being insulated.

4. A muffler comprising means providing an outer shell having an inlet adjacent one end and an outlet adjacent the other, there being a continuous straight unobstructed passage through the shell from the inlet to the outlet, means providing a series of outwardly extending cavities within the shell adjacent the inlet, said cavities being closed except around said passage, said cavity providing means being in spaced relation to the inner wall of the shell and from the inlet whereby a portion of the gases entering through the inlet may pass directly into the passage and the remainder of the gases flow around the cavity providing means toward the outlet, converging means in the shell adjacent the outlet for converging the gases toward said passage before passing into the outlet, and means connecting the cavity providing means and converging means enabling them to be removed from the shell as a unitary structure.

5. A muiller comprising means providing a shell having an inlet and an outlet, a series of conical baffles having aligned apertures disposed in the shell, said bailles being directed forwardly toward the inlet, and means providing a wall around the bailles in spaced relation to the interior of the shell providing a space in communication with the inlet through which a portion of the gases entering the inlet may flow.

6. A muler comprising means providing a shell having an inlet and an outlet, a series of forwardly directed conical baffles having aligned apertures disposed in the shell, and means providing a Wall around the bailles forming therewith a series of circular cavities open only at the passage formed by the aligned apertures, said wall cooperating with the shell to form. a space surrounding the baffles that is open to both the inlet and the outlet.

7. A muffler comprising means providing a shell having an inlet and an outlet, a series of forwardly directed conical bailles having aligned apertures disposed in the shell, and means providing a wall in spaced relation to the interior of the shell around the baffles forming therewith a series of annular cavities open only at the passage formed by the aligned apertures, the space between the wall and the Shell being open to both the inlet and the outlet.

8. A muiller comprising means providing a shell having an inletadjacent one end and an outlet adjacent the other, a series of conical bailles within the shell having aligned apertures opposite the inlet, said baflies being directed forwardly toward the inlet, means providing a wall around the baffles in spaced relation to the shell, said wall cooperating with the shell to provide a space open to the inlet and the outlet through which a portion of the gases entering the muffler through the inlet may pass. i

9. A mufller comprising means providing a shell having an inlet adjacent one end and an outlet adjacent the other, a series of conical bailles within the shell having aligned apertures opposite the inlet, said bailles being directed forwardly toward the inlet, means providing a wall around the bailles invspaced relation to the shell, said wall cooperating with the shell to provide a space open to the inlet and the outlet through which a portion of the gases entering the mufer through the inlet may pass, and a series of conical baflles in the shell having aligned apertures opposite the outlet, the last-mentioned series of baffles having their edges in spaced relation to the walls of the shell and being directed rearwardly toward the outlet.

10. A muiller comprising means providing a shell having an inlet adjacent one end and an outlet adjacent the other, a series of conical bafes within the shell having aligned apertures opposite the inlet, said baffles being directed forwardly toward the inlet, means providing a wall around the baffles in spaced relation to the shell, said wal] cooperating with the shell to provide a space open to the inlet and the outlet through which a portion of the gases entering the mufller through the inlet may pass, the interior of the shell being lined with insulating material.

WILLIAM B. MCLEOD. 

